In celebration of Earth Day, a day on which more than 155 countries were signing a landmark U.N. agreement on climate change, here are five reasons Earth is not as doomed as you think.

Know of others? Please share 'em in the comments.

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1. 195 countries have agreed to fight pollution

We truly are at a turning point in history. December 2015 is when 195 countries agreed to tackle the Earth's most pressing crisis: climate change. The Paris Agreement, which was negotiated at the COP21 U.N. climate change summit in the wake of the Paris terror attacks, shows that the world is more unified on this issue than on perhaps any other.

The Paris Agreement sets the bold goal of ridding the world of fossil fuel pollution this century -- and limiting warming to well below 2 degrees Celsius.

The accord was was decades in the making. And it is absolutely critical if we're going to pass a livable planet on to future generations. This is the beginning of the end of dirty fossil fuels. And it's great cause for celebration.

2. Solar energy has gotten waaaaay cheaper

If we're going to beat climate change, we have to stop using dirty fuel sources such as coal, oil and natural gas. The clean replacements? Things such as wind and solar. It looks like we're finally entering the solar era -- and that's at least partly because solar power is getting so much cheaper.

Luminaries such as Bill Gates are also gathering billions in funds to work on "moonshot" technologies that could help us meet the climate goals that are outlined in the Paris Agreement. We're likely going to need advanced nuclear technology and possibly carbon-capture technology to halt warming short of 2 degrees. More investment is needed, but there are important signs that we're starting to make these bets on the future.

4. Electric cars are getting popular

Gas and diesel cars are big polluters. The transit sector accounts for about 15% of all global warming pollution. But guess what? Electric cars are catching on in a big way. And as the electricity system becomes cleaner, too, that means that huge chunks of global emissions will be eliminated.

We all know who to thank for this: Elon Musk. That semi-robotic, kinda scary, kinda brilliant tech visionary seems to be operating on the presumption that everyone will be driving electric cars in the not-super-distant future. The Tesla Motors founder earlier this year debuted a $35,000 electric car. That's seen by many people as a monumental shift -- a sign that high-end cars will soon be available to the masses. Bloomberg New Energy Finance predicts electric vehicles will make up 35% of global new car sales by 2040.

5. China finally is starting to clean up its act

Finally, China. It's the world's scapegoat when it comes to climate change. The line goes: Well, China's not doing anything about its pollution -- and we all know about its pollution -- so why should we?

The trouble with this: It's fundamentally untrue.

Not only is China pledging to sign and ratify the Paris Agreement, it is experimenting with carbon-pricing systems to reduce pollution and plans a national carbon market that it says will be in place next year. The United States sure hasn't done that. And a five-year plan announced earlier this year says China will do more to cut its pollution than previously thought.

"With China's new target for an 18% reduction in carbon-intensity from 2015 levels, we estimate that China will actually reduce its carbon intensity 48% from 2005 levels by 2020," the World Resources Institute says in a blog post, "exceeding its original target of a 40% to 45% reduction by that year. It will also be a first step toward achieving its Paris Agreement pledge to reduce carbon intensity 60% to 65% by 2030."